The Fifth Doctor, Tegan and Turlough, reunited with Nyssa in Cobwebs, find themselves in a mysterious human colony where the original settlers have forgotten what they are there for and are now the prey of mysterious forces. To be honest the plot isn't the strong point here, but Lyon is rather good at catching the dynamics of Team Tardis of 1983, and Hayley Attwell turns in a notable guest performance as the potential young leader of the locals. A decent enough sf play which would engage but not fascinate the non-Who fan; sometimes that is enough.